Method oe forming- molds fob pb



July 10, 1928.

L. CLAYBOURN METHOD OF FORMING MOLDS FOR PRINTIG PLATES 3 Sheets-Sheet l Filed May 9, 1927 FouNDATnoNS l WHEN Yau BUILD, BUn-D RlGHT use JQHN no: BLGCKS Aegean :an lvanv Punvom:

July 10, 192s. 1,676,692

L. W. CLAYBOURN METHOD OF FORMING MOLDS FOR PRINTING PLATES Filed May 9. 1927 5 sheets-sheet 2 vI i7 24. l-Q Z July w, wm, 3,676,662

L.. w. cLAYBouRN METHOD OF FORMING MOLDS FOR PRINTING PLATES Filed May 9, 1927 3 Sheets-Sheet 3 fig- Z 7...

inatented July itl, i928.

ii fel l Fi 'a are' 'a' fa ."K' @naar Filets.

LESLIE W. CLAYBOURN, O MILW'JEUKEE, VISCONSIN.

METHOD 0F FORT/LING MOLS FOR RNTING FLATES.

application area May e, 1927. sel-a1 No.- 189,894.'

My invention relates to a method of forining a inold for a printing; plate .vhereby the inold is provided with a bearei area or bearer areas, for the provision. in the printing` plate formed from said mold, of a hearing surfare or hearing` surfaces in the plane of the printing surface ou said plate` so arranged on the printing plate as to aid in resisting' pressui'e upon the printing' portion or printing); portions of the printing' plate, or to aid in equaliZing said pressure tl'iroun'hout the area of tl e printing plate., and whereby, further, 'the printing plate is provided with a bearer area or bearer areas for aiding in ecpializine' the bending' stresses upon the pri ting plate duriig; the curving of the printingIf plate when forniine' a flat printing;` plate into a. eurved printinpT plate.

it is a practice in the inodern u'iakingg' of printingplates to exert pressure upon the printing;` plate While the printing' 'surface thereof is resisted by a. smooth hard surface, in order to brine; the various printing surfaces of the printing' plate into the saine plane, whether the plate be fiat or curved, the plane in the instance of curved plates being; a Cylindrical plane, and it is also the practice to bend a. flat. printing plate in order to form a Curved printing' plate suitable for instance for application to a plate eylins'ler of a rotary printing' press.

Many printing' plates are provided with printing portions in only a part or in separated parts of the area thereof, and many other printing' plates are provided With printing,r portions Which are more Compact, or in which the printing lines are broader, in seine portions of the printing; plate than in others, ivith the result, When pressure is applied to Coinpress the printingr plate, or to press all parts of its printing portions into the saine plane, that uneven resistanees to the pressure forces are found in different parts of the printing plate, those parts With light, fen' or separfV ed printing surfaces being obliged to resist the saine pressures as those parts with inore condensed printing,surfaces` or larger printing areas, in consequence of which the light or separated printing' surfaces and the edges of printing areas are unduly pressed, and a printing plate is produced which is not perfect.

It has also been found that upon bending' stresses being applied to printing plates having' unequal or unbalanced areas of printing' portions, that unequal resistanees to said bending' stresses are' found in the various portions of the printing' plate. depending on the unevenness of the. distribution of the printing surfaces thereon. and a curved printing' plate is produced which is irregular in its curvature, or in the location of Yall its printing surfaces in the saine cylindrical plane.

It is the -o-bjeet of my invention to provide a inold with depressions eoniplelnental to the depressions niade therein by the printers forin, such forni being a forni of type, Cuts and the like, or previously made printing plates. or any one or more of these; further, to provide a niold for a printing' plate` which las been previously provided with depressions ofthe printing' surfaees of the printing forni, with additional depressions formed in the unprintinfr portions of the mold, so that., when the printing plat-e has been formed frein such mold, as by electro-depositing, Casting or other process, or one or more of the saine, there are printing` areas and bearer area of equal height Well distributed throughout the printing' plate, for forming' the printing plate at its various portions of equal thickness in order to resist pressure, bending,r stress. or the like, to substantially equal extent. throughout the area of the printing plate.

It is the object of iny invention, further, to provide a previously formed niold for a printing' plate having' depressions of printareas therein. with additional depressions of depth equal to the dept-h of the depressions of the printingl characters of the inold, for performing the mold Wit-h depressions of printing areas, and then forming the inold ivith additional depressions of bearer areas by removing' portions of the imprinting' parts of the niold.

It is the object of my invention further, to provide a \va;\' inold` provided with pre viouslv forn'ied printing' depressions, with after-formed depressions in imprinting' parts, by removing' portions of the face side of the mold past the surface thereof to a depth equal to the depth of the printing depressions; further, to perforin the Wax mold having depressions therein of printing' portions and an imprinting area, and to eut away said imprinting` area or a portion (ill thereof by a cutting edge reaching into the body ot' said unprinting area to a depth gaged by the depth ol the printing depressions and causing movement between said mold and said cutting edge in the plane o't' the bottom ot said vprinting depressions, for providing the mold with bearer forming portions, so that the printing plate formed by the inold will have therein printing areas and bearing areas of equal height.

The invention will loe 'further readily un derstood Afrom the following description and claims, and it'roin the drawings, in which latter:

F ig. 1 is a plan view of a inold having therein areas of printing portions and areas of imprinting portions, to which my irnproved method may be applied.

Fig. 2 is a cross-.section of the saine, taken on the line 2-2 of Fig. 1.

Fig. 3 is a cross-section of the saine, taken on the line 3-3 ott Fig. 1.

Fig. 4 is a plan view of the same mold having my invention applied thereto.

Fig. 5 is a cross-section of the same., taken .on the line .5-5 of Fig. 4, showing the aftertorlned bearer-depressions in the mold.

Fig. 6 is a cross-section of the same, taken on the line 6 6 of Fig. 4..

Fig. 7 is a plan view ot a printing plate, which may be an electrotype, made from the mold shown in Figs. 1, 2 and 3..

Fig. 8 is a cross-section of the saine, taken on the line 8-8 of Fig 7.

Fig. 9 is a cross-section of the saine, taken on ,th-.e line 9 9 ot Fig. 7.

Fig. 10 is a plan view of a printing plate made from a mold shown in Figs. 4, 5 and 6, having my invention applied thereto.

F ig. 11 is a eross-section of the same, taken .on the line 11-11 of Fig. 10.

Fig. 12 a. cross-section of the same, taken .on the line 12-12 of Fig. 10.

Fig. 13 is an enlarged detail of the latter.

Fig. 14 is a front elevation of an appara- .tns employed in the performance of my imA proved method.

Fig. 15 is .a side elevation of the saine, partly broken away.

Fig. 16 is a fragmentary rear elevation of the saine.

Fig. 17 is a plan view of the same.

Fig. 18 is a vertical longitudinal section ot' the same. taken on the line 18-18 of Fig. 17. and partly broken away.

Fig. 19 is a tragniientary vertical crosssection ot' the saine, taken on the line 19-19 o1 Fig. 17.

Fig. 20 is a cross-section of the saine, taken on the line 20-20 of Fig. 19.

Fig. 21 is a detail of the positioning means for the cutter, taken in section in the plane of the line 21-21 of Fig. 18.

Fig. 22 is a crosssection of the same taken in the plane of the line 22-22 of Fig. 18.

Fig. 23 is a detail of the stop for the cutter operating bar, taken in section on the line 23-23 of Fig. 16.

Fig. 24 is a side elevation o1 the cutter in its socket, the latter shown in vertical section; and,

Fig. 25 is a cross-section ot the saine, taken on the line 25-25 of Fig. 24.

The printing plates may be clectrotypes, stereotypes, or printing plates otherwise formed, or formed of different material. The printing plate 31 is exenlplilied as an electrotype, (see F' 9 and 13), which coniprises. an electro-deposited shell 32 and a backing 33 oli metal cast in the shell.

In the modern practice of correcting printing plates it is usual to support the printing surface ot' the printing plate by a sinooth hard surface and to apply pressure to the printing plate for bringing all the printing surfaces thereofl into the saine plane, as shoi'vn, described and claimed for instance in United States Letters Patent No. 1,549,185, granted to ine August 11, 1925, tor in'lln'oveinents in inethod of correetingprinting plates and printing plates produced thereby.

It has been found, in applying pressure upon a printing plate which has unbalanced areas ol printing surface, that those portions oi' the printing plate, as at 34, which have restricted or small areas ot printing surface, and the edges ot printing portions oil the printing plate adjoining unprinting portions, are less resistant to the pressures applied to the printing plate, than the printing portions thereof, as at 36 (Fig. 7), which have greater areas ot printing surface, with the result that such portions of less resistance are likely to be and olten are deformed or spread. in a manner to mar the excellence of the printingplate.

It has also been found, in .curving printing plates thus formed with unbalanced printing areas, that the kthicker portions oi the printing plates resist the bending stresses to greater extent than the thinner portions, resulting in a curved printing plate in which the printing surfaces are not in as true cylindrical t'orin as they should be. or in which the curvature of the printing plate is irregular.

In order to avoid these objections.I I provide the imprinting portions ot the printing plate, as at 37, (Figs. 7. S and 9), with ad ditional thickness so to balance the resistanees ot the printing plate throughout its area. I accomplish this by providing the printing plate with additional bearers in the unprinting pei-tions thereof, or in the spaces adjacent to the printing portions. as er-:einplitied by the raised portions or bearers 38 in the printing plate. (See Figs. 10, 11, 12 .and 13.)

These bearers aid in resisting the pressure applied to the printing plate in correcting the saine, and aid in resisting the bending stresses when curving the printing plate, so that excess pressure is taken off of the isolated printing parts of the printing plate, and crushing, deforming or mutilation thereof is avoided, and for providing a uniform body for the printing plate in which the resistance to bending stresses are substantially evenly distributed for enabling a uniform curvature to be applied to the plate.

After the printing plate has been corrected, or curved, and otherwise completed, as the case may be, the eXtra bearers are removed by routing, or in other desirable manner, for instance, to the dotted line 39 in Fig. 13, so that the imprinting portions of the printing plate are in properly low relation to the printing portions of the printing plate for proper inking and printing. The printing plate is formed from or upon a mold, which has in it the reverse counter parts of the printing plate formed thereby.

The mold may be of suitable character, but is insta-need as a usual Wax mold 42, comprising a layer or sheet of Wax in which an impression of the printing form is made by pressure, this layer or sheet of Wax being uponv a backing sheet of metal. The mold, as thus made, referring to Figs. l to 3 inclusive, is instanced as embodying printing portions 44, 45, 46, and imprinting portions 47, corresponding to the printing` portions 34, 35. 36, and the imprinting portions 37 in the printing plate and corresponding portions in the form from which the moldr is made. This form is surrounded by a line of form bearers, the depressions of which are shown at 48 in the mold. These form bearers are at the outer margins of the form and are provided primarily for the purpose of preventing lateral shifting of the form on the mold when pressure is applied. The depths to Which the printing portions of different forms are pressed into their respective molds vary.

Whenever printing portions, imprinting portions, and bearers or bearer portions of the mold are hereinafter mentioned, it Will be understood that those portion-s of the mold are referred to from which the printing portions, the unprinting portions and the bearers or bearer portions respectively of the printing plate are formed, these respective portions in the mold being the reverse in 'elevation and direction of the corresponding portions in the printing` plate formed therefrom.

In my invention, I therefore first form the mold with the usual printing areas, and the usual unprinting'areas, the lat-ter being represented in the mold by the retained thickness of the ymaterial of the mold, or by leaving such portions of the mold unimpressed.

I provide the mold thus preformed, with after-formed bearer-depressions, which in the mold are represented by additional depressions 51, (seeFigs. 4, and 6), formed in the mold by removal of material therefrom to a depth equal to the depth of the impressions of the printing characters in the mold. These bearer-depressions may assume various shapes, and extend throughout different areas, depending on the arrangement and character of the printing surfaces ivhich are formed in the mold by the printing form, the object being to associate such printing portions of the moldL thus preformed with after-formed bearer-depressions of equal depth adjacent thereto, so as to relieve slight or separated printing areas or characters in the printing plate formed from the Vmold of undue pressure, and to transfer the resistances to such pressure to the additional bearers thus formed in the printing plate as counterparts of the bearerdepressions thus formed in the mold.

It is desirable to form these bearer depressions in the mold by removal of material from the face side of mold, and it is desirable that this removal shall be accurately accomplished so as to provide bearer depressions Which are equal in dept-h to the depth of the printing depressions. I prefer to accomplish this removal by means of a cut-ting edge of a cutting tool which is sunk into the imprinting portions of the mold to a depth equal to the depth of the depressions of the `printing characters in said mold, and to cause travel between such cutting edge and the mold Iso as to form a groove or grooves in said imprinting portions of a depth equal to the depth of the printing depressions, the cutting tool removing the material of the groove o1` grooves past the surface of the face side of the mold.

This removal may be accomplished by a single passage between the tool and the mold, With the tool at extreme depth in the mold, namely in the plane of the bottoms of the printing depressions, or by a number of such passagesv to remove the material of the mold in successive steps in each of which the tool is deeper in the mold, until in the final passage the tool is in the plane of the bottoms of the printing depressions in the mold.

I prefer that the travel between the cut-V ting edge and the mold shall be in various directions, depending on the shape of printing areas adjacent to the imprinting port-ions and the eirtent` of such imprinting portions.

After the bearer depressions have been cut into a Wax mold, any rough edges left by the cuttingvtool are smoothed or removed b v the momentary application of a -hot blast which melts such rough edges. y

I have exemplified an apparatus by which such formations in the imprinting portions lim Liv

o1 the mold may vbe accomplished, although such format-ions may be obtained hy other means, or lby other manipulations, not herein more particularly disclosed.

The apparatus exemplified. comprises a bed 61, pported on -a suitable base, show-n ,comprfy 4ng legisgti?, rigidlv secured to the base, and tied together by tiefrods.

A. carriage A65 is slidable on guides 66 on the bed, the carriage being provided with guidewavs t3? cemplemental to the guides.

I The mold 42 is' arranged to be ri-gidl5Y held to the carriage :so as to lie flat on the plane supporting surface et the carriage, as by means of clamps 68. The carriage provided with an undercut groove 69, in which a base '70 provided with tongues is arranged to slide. A :clamping arm '14'1 is pivoted to the base by a pin 2 located in hearings of lugs in the-hase and in the. arm. A screw-rod 73 is held downwardlv iv its head being received in .a recess 74 in the base. The sere-inbred passes t ely.T throi-igh va hole 75 in the clamping vari A nut 70 is received over ythe threaded i'iortion of the screw-rod and has a handle 7L? bv means of which the nut may he readily turned for .clamping the clamping .shoe 7S of the. clamping arm upon the mold. clamping the mold to the carriage. A spring 7.9 hetwcen :said arm and said hase normally urges the clamping arm in unclamping di tion.

A screw-rod 81 is journaled in bearings 83, in the bed. and is held endwise therein by collars 84, 85, pinned to the screw-rod. A hand-wheel 816 and handle 87 thereon are arranged to turn the screw-rod. A nut 88 depend-s from and is fixed to the carriage and is threaded to the screw-rod. Rotation of the screw-rod moves Athe carriage in 4one direction or the other along the 'guides there -for on the bed according tothe Idirection of rotation of the hand-wheel.

A cutter 91 having a cutting edge 92 is arranged to coact with. the mold on the carriage. The cutter is releasablv secured to a cutter-har 93, as bv insertion of its shank in a socket 95 in said cutter-bar, and the clamping of said shank in said socket by means ot a set-screw 96 lxaving a turning lfnob 97 thereon. Cutters having lcutting edges ot different widths or shapes are arranged to be interchanged in cutting position on the cutter-bar.

'The cutting edge is adjustable toward an from the supporting face' o-t the mold tor determining the depth ot the cut to he made in `the mold. and means are provided tor moving said cutting edge toward and trom the mold for moving the cutting edge into and out of the face side ot the mold. and means are provided for positioning the direction in which the cutting is presented for presenting the cutting' edge in proper relation according to the direction of movement between the cutting edge and the mold. i The cutter-,ba r is mounted in hearings 101, 102, on a .slide 103. The cutter-bar is positioned endwise in said bearings, 4asby locating the bearings between a shoulder 104 on said bar and a handle 1.05 ixed to the opposite vend of :said bar. The cutter-bar is rotatively positioned in said hearings, and 'is provided with recesses 106. which recesses are shown 90o. apart. A ball 107 in a socket 108 in v.the Wall of the bea-ring' 101 is normally urged toward said cutter-bar by a spring 109 in said socket. The ball is received in said respective recesses for maintaining the cutter-bar in adjusted position during' the cutting operation.. y

The slide 103 is mounted on a rocker-arm :111 and is adjustable to elevation thereon. A screw 112 is journaled and heldl endwise in a bearing 113 on a bracket 114 on said slide. and is threaded into a threaded hole 115 in said arm. 'The screw-rod is provided with handle 116 for ready rotation of the saine. Rotation of the screw :adjusts the screw up or down, according to the direc/- tion of rotation` for positioning 'the cut-ting edge. The slide is slidable in a guideway 117 in the arm. The slide is clampedto the arm after adjustment b v means fof a clampsc-rew 121 extending through a, .slot 122 in the `slide and threaded into threaded hole 123 in the arm. A `washer 124 is received between the Walls of said slot 'and a head 125 on said screw. A handle 126.4is .fixed to said head for manipulation of the screw.

The arm is pivoted tov .and adjustable lengthwise of a screw-rod 131 jonrnaled in :bearings 132, 133, upon brackets 134, 1.35, exten/ding from the bed. 'The screw-rod is held endwise in said bearings by shoulders 136, 137, coacting with said bearings. A hand-wheel 138 having a handle 139 there on is fixed to said screw-rod for rotating the saine. When the screwaod is-rotated, the arm 1,11 is moved crosswise of the bed in one direction or the other, depending on the direction ot' rotation of the screw-rod.

The rocking movement of the rocker-arm is obtained by a bar 141 received in fork 142 in said rocker-arm. The respective ends of the bar are received in guideways 143 in the inner faces of brackets 144 extending from the brackets 134, 135. The rocker-arm moves lengthwise of said bar during the lateral travel of said rocker-arm. rlhe faces of the bar eoacting with the faces oi thevfork in said rocker-arm are preferably rounded, as shown at 145, for accurate movement of the rocker-arm and close engagement between the engaging surfaces of said bar and said fork throughout the lateral oositions and rocking movements of the rocker-arm.

Stops 151 are provided at the respective ends of the bar. These stops are shown as clips for closing the upper ends of the guidelll() ways 143, and are secured to the brackets 144 by bolts 152. These stops limit the extent of movement of the cutting edge into the mold, and, with the adjustment of the cutter slide, detern'iine the depth of the cut made by the cutting edge. i

Movement of the cutting edge out of the mold is obtained by the retracting movement of a treadle 155, on a treadle-lever 156, which is pivoted on a tie-rod 157 between the side frames of the base, and is articulated at 158 with a link 159. The link 159 has articulation` at160 with an arm 161 fixed toa rocker-rod 162 journaled in bearings 163 on brackets l164 extending from the brackets 134, 135.

Rocker-arms 165 are fixed to the respective ends of said rocker-rod and have articulations 166 with links 167 having articulations 168 with the respective ends of the bar 141.

A spring 171, the respective ends of which are secured to the tie-rod 172 and to the treadle-lever 156 normally holds the treadlelever in raised relation, and urges movement of the bar 141 away from the stops 151. The cutting edge 92 is normally positioned at its limit of movement away from the bed.

If it is desired to operate on a mold, the mold is slipped under the cutter and clamped to the table. The cutter-support is adjusted laterally by rotation of the handwheel13'8, and, if necessary, the carriage is moved by rotation of the hand-wheel 86, to position the cutter at a printing depression in the mold, the cutter being out of Contact with the mold. The cutting edge is caused to descend into said printing depression by depression of the treadle and the height of the cutting edge is adjusted by rotation of the hand-wheel 116, so that the cutting edge just touches the bottom of said printing depression. The cutter-slide is then clamped in adjusted position. It is to be understood that whilst such adjustment is being made, the slide-bar 141 is in contact with its stops 151` for definitely limiting the downward movement of the cutting edge.v

The treadle is then released for raising the cutter out of the printing depression, and the cutter frame is adjusted laterally, by operation of the hand-wheel 138, and, if necessary, the carriage is moved by rotation of the hand-wheel 86, to locate the cutting edge in a position at the unprinting portion of the mold which it is desired to provide with abear'er depression. The cutter-bar 93 is rotatively set by rotation of the handle 105 to present the cutting edge in desired direction for the direction of desired movement between the mold and the cutting edge. The cutter is then moved into thel face side of the mold by pressing on the treadle. The

desired movement is then imparted either by. the hand-wheel 86 for moving the oarriage, or by the hand-wheel 138 for moving the cutter, as may be desired, or the direction of presentation of the cutter may determine, or by both said hand-wheels if a diagonal path of the cutter is desired. The screw-rods 81 and 131 may have threads of comparatively high pitch for rapid traverse off the cutter and-carriage for rapid operation.y

Assuming that a path isv desired to form a parallelogram 175 in the printing portion ofthe mold, the cutting edge is presented in a direction transverse to the carriage and the carriage moved rearwardly. The cutting edge isthenrotated 900, and the cutterhead moved laterally in one direction. The cutter-bar is then rotated another 90, and the carriage moved forwardly the desired extent. The cutter-bar is then rota-ted another 900, and the cutter-head caused to travel in the opposite direction to complete the parallelogram.

1f desired, the depth of cut may be obtained by successive settingsv and cuttings, each removing a portion of the thickness of material for forming the depression, until the depression is of the desired depth.

It is desirable that the area of bearei depressions in the mold shall be gaged by the density of the printing portions in the mold. Thus if the printing portions be close or dense, lthe bearer portions in the unprinting portions will be made dense, and if the printing portions be light, the bearer portions intlie imprinting portions will be made correspondingly light, to produce uniformity inv thickness in the printing plate.-

The action of4 the cutter is preferably to remove the chips arising from the cutting past the upper surface of the mold, and the form of the cutter is preferably such that sharp outlines of the walls and bottom of the groove being cut are formed, and a sharp upperedge for said walls is provided. It will be noted that the advancing side of the cutter is hollowed adjacent to its cutting edge, the body of the cutter receding as shown at 177 above the cutting edge, and then curving forwardly, as shown at 178, for ready relief of the removed strip of the mold. The sides of the cutter adjacent to the cutting ledge and throughout the walls of the grooveformed by the cutter are sharp, for making clean cuts at the bottoms, sides and upper edges of said walls.

Closely adjacent parallel grooves may also be cut in said imprinting portions of the mold, as well as grooveswhich merge into each other, and other forms and relations of grooves may be cut, or any desired direction, width or shape of grooves or corelation of grooves may be cut, as may be desired.

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I The mold may be clamped on the' carriage with its sides pa allel with the sides of the carriage, as shown in 17 or said ino'l'd may be clamped in any desirable angular position, depending on the directions 1n which it is desired to out the grooves in the mold. These grooves are desirably cut pare allel with adjacent printing lines, so that, if' the printing lines` are angular with relation to the mold, the mold is desirably angularly clamped ony the carriage. n

1When the printing plate is formed from a mold formed as herein described, the after-"formed bearer depressions are reproduced with the printing depressions in the printing plate as bearers and as print-ing ele vations respectively, of equal height, for formino; a printing plate in which the printing po. ...ons which are weak in resistance to pressure or bending stresses, are strengthened by the bearers thus provided, for producing a prii'itiirig plate in which the printinlfjej portie are protected from injury by pressures applied to the printing plate, and

p in which all portions ot the printing surface are uniformly4 bendabl'e 'for providing a curved printing plate properly curved tl'iro'ugl'iout.

I do not herein cla-im the mechanism, exempliiied employed in connection with niv improved method.r having shown, de-4 scribed' and claimed the saine in a @opendinlg application iiled by ine in the United Statesluatent 'lhce May 16, 1927, for patent on improvement in mold' bearencutting inachine, as Serial No. 191,915.

lhat I do claim herein as my invention and desire to securel by Letters Patent, is:

1. A method' of forming a nlold for a printing plate which includes making a mold' of the form whereby depressions of i the printing portions are lformed in the face side of the mold', and then removing a portion of said liace side ot the mold in which such depressions ot printing` portions have not been formed toy an even depth equal to the depth o-'t said previously formed deinessions, and tliereby forming a. depression in said tace side ol' said' mold for bearer area on the printing plate 'formed from said mold.

2. il. .rnethod of forming a mold or a printing plate which includes making a n'i'old ot the forni whereby depressions of the printing portions are 'formed in the face side of the mold, then removing a portion of said face side ot the mold in which such depressions o'lVprintin-g portions have not been formed' to an even depth equal to the depth of said previously formed depressions, and thereby forming a depression in said face side of said mold for bearer area ou the printing plate'lorined from said mold and then iiuishing the edges ofl said last-named depression.

3. A method of forming a mold for 1a" printing. plate which includes making a mold of the form whereby'depressions of the printing portions of the form are formed in the face of the mold extendingv t. A method oit forming a mold for aIV printing` plate which inchid'es nialii-ng a moldI oi the forni whereby depressions of the printing portions oi' the form are formed in the molid and then removing portions of the tace sicie ol the ino-ld in which such depressions oi printing portions have not'been `formed by a tool whose position and angle with relation to the bottoms of said depressions are maintained to Yform bearer incisions of uniform depth eqn-al to the depth of said first-named depressions.

5. method ot' forming anrold for' a prin-ting plate which includesmaking a mold. ot" the iorn'i whereby depressions of the printing portions oi-` the torni are formed in the tace side of the mold, and4 then causting movement in parallel planes between said mold and a cutting tool whose angle of presentation tol said tace side is maintained during the cutting' and whose cutting edge is Vbelow the surfaceo'f saidtace side to' depth equal to the depth of the bottoms oi" said first-named depressions from said sur'-4 ace tok form bearer depressionsl in said mold.

(i. A method oi forming a Wax mold for a printing plate which includes ornrin' depressions ot the printing .portions of a ornil inthe face side ot a wax sheet by pressure, and then eau-sing relative movement in parallel planesv between' said Wax mold and a cutting edge under the outer surface ot said tace side at a depth. equall to' the depth of the bottoms of said first-named depressions un'der said surface Ytor removing other portions of said face side and' forming bearer depressions ot said depth.

7. A method of forminga wax mold for a. printing plate which ineludes forming` depressions of the printing portions of a form' in the face side oiV aivax mold by pressure, then gaging the depth of entrance' of a tool into said face side of saidf wax nilold by the bottoms oit said lirstgnanied depressions in said' wax mold, and then causing coaction between saidtool and `imprinting portions of said. wax mold at said depth so determined forl forming' bearer depressions of' said depth in said Ytace side of said imprinting portionsof said wax. mold'.

8. A method' of forming al mold for a printing plate which includesA making a mold of the forni whereby depressions of the nro lll)

printing portions are formed in the 'face side ot the inold, setting a cutting edge in the plane of the bottoni face of said depressions und causing travel in a plane parallel with said bottom face between undepressed portions of said mold and said cutting edge and thereby removing undepressed portions of said mold, whereby to provide the printing plate formed by said inold with bearers at its imprinting portions of equal height 10 With the height of said printing portions.

In testimony whereof, I have hereunto signed my name.

LESLIE W. CLAYBOURN. 

